LONDON (Reuters) - Boris Johnson’s decision to suspend parliament for five weeks was unlawful and should be annulled, Scotland’s highest court of appeal ruled on Wednesday in a damning verdict on the British prime minister’s reasons for the shutdown.

Parliament was prorogued - suspended - on Monday until Oct. 14, a move opponents argued was designed to thwart their attempts to scrutinise his plans for leaving the European Union and allow him to push through a no-deal Brexit on Oct. 31.

“You cannot break the law with impunity, Boris Johnson,” said Joanna Cherry, the Scottish National Party lawmaker who led the challenge. “We are calling for parliament to be recalled immediately,” she told Sky News after the unanimous verdict by three judges at Scotland’s Court of Session.

Johnson’s office said the government would appeal to the Supreme Court, the highest judicial body in the United Kingdom. It was not immediately clear what effect the ruling would have.

A government official said Johnson believed parliament remained suspended pending a ruling by the Supreme Court.

Johnson announced on Aug. 28 that parliament would be prorogued, saying the government wanted the suspension so it could then launch a new legislative agenda.

Opponents said the real reason was to shut down debate and challenges to his Brexit plans. The court was shown documents that showed Johnson was considering prorogation weeks before he formally asked Queen Elizabeth to suspend the legislature.

“The UK government needs to bring forward a strong domestic legislative agenda,” a government spokesman said in response to Wednesday’s ruling. “Proroguing parliament is the legal and necessary way of delivering this.”

Britain's Prime Minister Boris Johnson speaks with year four and year six pupils during a visit to Pimlico Primary school in London, Britain, September 10, 2019. REUTERS/Toby Melville/Pool

“CLEAR FAILURE”

However, in an excoriating judgement, the Scottish judges ruled the principal reason for suspension was to stymie lawmakers and allow Johnson to pursue a no-deal Brexit policy.

“This was an egregious case of a clear failure to comply with generally accepted standards of behaviour of public authorities,” concluded one judge, Philip Brodie, according to a summary of the court verdict.

Judge James Drummond Young had determined that “the only inference that could be drawn was that the UK government and the Prime Minister wished to restrict Parliament,” the summary said.

“The Court will accordingly make an Order declaring that the Prime Minister’s advice to HM (Her Majesty) the Queen and the prorogation which followed thereon was unlawful and is thus null and of no effect.”

Cherry and other lawmakers, including some parliamentarians who were thrown out of Johnson’s Conservative Party last week for rebelling over Brexit, said parliament should be recalled without delay.

One of the former Conservatives, Dominic Grieve, said if Johnson had misled the queen over the reasons for prorogation, he should resign.

“If that were to be the case that this had happened, Boris Johnson would find himself in an untenable position in parliament,” Grieve told BBC TV.

Britain's Prime Minister Boris Johnson speaks after Britain’s parliament voted on whether to hold an early general election, in Parliament in London, Britain, September 10, 2019, in this still image taken from Parliament TV footage. Parliament TV via REUTERS

Asked whether Johnson had misled the monarch, his spokesman said they had publicly given their reasons for the suspension.Buckingham Palace declined to comment on the ruling, saying it was a matter for the government.

A lower Scottish court had originally rejected the challenge and last Friday, London’s High Court also dismissed a similar challenge by campaigners. In their full ruling, published on Wednesday, the judges ruled the issue was not a matter for the courts.

An appeal in that case is due to be heard on Sept. 17 at the Supreme Court.